Strange blooming (?) issue with my ZWO ASI 120 MM-S

Equipment CMOS Artifacts
2 replies•113 views
Georg Gruetter avatar
Georg Gruetter avatar
Hi all,

I'm experiencing a strange imaging issue with my ZWO ASI 120MM-S. There's a wedge shaped shadow in all bright stars. I think I can exclude my telescope (8" F/4 Newtonian) as my DSLR does not exhibit the same behavior. Here's a crop from a representative sample:



Does anybody here have a clue as to what could cause this? Thanks in advance for your help!

Cheers,
Georg

Georg Gruetter avatar
Georg Gruetter avatar
It turns out, that this is not a problem of my camera. I tried a different camera today and got a very similar result. So it's obviously my OTA. I have no idea what could cause this kind of problem, though. The collimation seems ok and there's nothing (like e. g. the focuser) that I can see which would cause this. Mirrors are reasonably clear, as well.

Again, any ideas are very welcome.
Jean-Christophe avatar
Jean-Christophe avatar
Hi,
nothing in the optical path, like drawtube?? I had a similar problem in the past.

Jean-Christophe